Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/28—Oxygen or compounds releasing free oxygen
  • C08F4/32—Organic compounds
  • C08F4/36—Per-compounds with more than one peroxy radical
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F14/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F14/02—Monomers containing chlorine
  • C08F14/04—Monomers containing two carbon atoms
  • C08F14/06—Vinyl chloride
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

• This invention relates to a process for the polymerization of vinyl monomers, and in particular to a process for the polymerization of vinyl chloride using a polymerization initiator comprising a diperester of oxalic acid, and to polymers prepared according to the process of the invention.
• the present invention provides a process for the production of a vinyl chloride polymer which process comprises the homo- or copolymerization of vinyl chloride at a temperature in the range of from 25° to 80°C and a pressure in the range of from 1 to 20 kg/cm 2 in the presence of from 0.01 to 2%, by weight of the monomer, of a diester of diperoxyoxalic acid of formula I wherein R 1 and R 2 are independently chosen from C 1 to C 6 alkyl, cyclohexyl and benzyl and at least one of Rand R 2 is a secondary alkyl group, a tertiary alkyl group or a benzyl group.
• R1 and R 2 include straight chain C 1 to C6 alkyl, branched chain C1 to C6alkyl, cyclohexyl and benzyl.
• Preferred R and R are C 1 to C6 alkyl and especially secondary or tertiary C 3 to C 6 alkyl.
• a particularly preferred compound of formula I is di-(tert-butyl) diperoxyoxalate.
• the process of the present invention may be applied to the production of vinyl chloride homopolymers or vinyl chloride copolymers containing at least 50 mole percent, and more preferably at least 80 mole percent, of units derived from vinyl chloride monomer.
• Monomers which may be copolymerized with vinyl chloride monomer include, for example: vinyl derivatives such as vinyl bromide, vinyl acetate, vinylidene chloride, N-vinylcarbazole, methyl vinyl ether, vinyl isobutyl ether and N-vinylpyrrolidone; a-olefins such as ethylene, propylene, butylene and isobutylene; acrylates such as acrylic acid, n-butyl acrylate, ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate and 2-ethylhex
• the polymerization process of the invention may be carried out using any of the operating conditions customarily used for the homo- or co- polymerization of vinyl chloride monomer.
• Conventional processes for the preparation of vinyl chloride polymers include bulk polymerization, gas phase polymerization and polymerization in an aqueous medium by suspension or emulsion polymerization techniques.
• vinyl chloride monomer is homo- or co- polymerized using an aqueous suspension process with the aid of one or more suspending agents.
• Suitable suspending agent(s) for use in the process of the present invention may be chosen from those conventionally used.in the art for the polymerization of vinyl chloride monomer in aqueous suspension.
• Such suspending agents include, for example, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydrolysed poly(vinyl acetate), gelatin, methyl vinyl ether - maleic anhydride copolymers, and mixtures thereof.
• a preferred suspending agent for use in the process of the present invention is partially hydrolysed poly (vinyl acetate) (PVAc).
• the degree of hydrolysis of the currently commercially available PVACs which may be used as suspension agents when the vinyl chloride monomer is polymerized in aqueous suspension according to the process of the present invention may vary within a large range.
• the degree of hydrolysis of the PV A c is in the range of from 20 to 90 mole %.
• the degree of hydrolysis is in the range of from 60 to 90 mole %.
• the partially hydrolysed PVAc_ may be used on its own as a suspension agent or in combination with a different type of suspension agent.
• the total amount of suspension agent used in the polymerization may vary widely and is generally between 0.05 and 2.0% by weight of the monomer.
• the polymerization process of the invention is generally carried out at a temperature in the range of from 25° to 80° C and preferably from 30° to 70°C.
• the pressure at which the polymerization reaction may be carried out ranges from atmospheric pressure to a pressure of 20 kg/cm 2 but the pressure is preferably 2 below 15 kg/cm .
• the high order of activity of the compounds of formula I enables the polymerization reaction to be carried out at lower temperatures and/or for shorter reaction times than can be achieved using the current commercially available "high activity" initiators.
• the polymerization of vinyl chloride monomer in aqueous suspension using bis(4-t-butylcyclohexyl) peroxydicarbonate (one of the most active commercially available initiators as initiator under conventional reaction conditions, at a temperature in the range of from 50-70°C takes of the order of 120 to 250 minutes for completion.
• the half-lives of the initiators acetylcyclohexane sulfonyl peroxide (ACSP) and bis(4-tert-butylcyclohexyl) peroxydicarbonate (BCHP; one of the most active commercially available initiators) are of the order of 30 minutes and 160 minutes respectively (measured in benzene at a temperature of 50°C) and therefore it might be expected that ACSP would be a considerably more active (faster) initiator than BCHP for the polymerization of vinyl chloride monomer.
• ACSP acetylcyclohexane sulfonyl peroxide
• BCHP bis(4-tert-butylcyclohexyl) peroxydicarbonate
• an initiator such as di(tert-butyl) diperoxyoxalate (a compound of formula I) with an even shorter half-life (of the order of 20 minutes measured in benzene at 50°C) than ACSP polymerizes vinyl chloride monomer to over 80% conversion of the order of at least 2.6 times faster than does BCHP.
• initiators of formula I results in the inclusion of only very low levels of "initiator residues" into the polymer, which may lead to improved polymer properties.
• the compounds of formula I decompose to generate the free radicals which initiate the polymerization reaction, the only products formed are the low molecular weight radicals R 1 0 . and R 2 0. and carbon dioxide. In effect, this means that on a weight for weight basis only very small amounts of material which did not originate from the monomer are incorporated into the polymer.
• While the process of the present invention is especially advantageous in the low temperature polymerization of vinyl chloride monomer it may also be used to advantage in higher temperature polymerizations using a mixed initiator system.
• a polymerization reaction according to the process of the present invention which employs a compound of formula I as the only initiator may not go to completion before the initiator is exhausted. If it is desired in the process of the present invention to utilize reaction conditions in which the initiator of formula I may be exhausted before the completion of the polymerization reaction, completion of the reaction can be effected by the use of a mixed initiator system comprising a compound of formula I and one of the less active, slower initiators.
• Suitable additional initiators may be chosen from those initiators known in the art to be suitable for use in the polymerization of vinyl chloride monomer including, for example, lauroyl peroxide, bis-(4-tert-butylcyclohexyl) peroxydicarbonate, dibenzoyl peroxide, diiscpropyl peroxydicarbonate, tert-butyl peroxypivalate, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, sulfonyl peroxides and the like.
• the compounds of formula I are highly active initiators for the polymerization of vinyl chloride monomer which decompose when heated. Moreover, some of the compounds may explode when scratched, rubbed or crushed. As a result it is important that the compounds of formula I be treated with care.
• reaction may be carried out in one step by reacting one mole of oxalyl chloride with two moles of the appropriate alkyl hydroperoxide.
• the reaction is preferably carried out at a temperature below 0°C in an anhydrous inert solvent such as an aliphatic or aromatic hydrocarbon.
• a base for example pyridine, may be added to the reaction mixture to neutralize the hydrogen chloride formed in the reaction.
• the compound of formula I used as an initiator in the process of the present invention may be prepared as described above and stored, preferably at a low temperature, until ready for use. Alternatively, if minimum handling and storage of the initiator is desired, the compound of formula I may be prepared in an adjacent reaction vessel and be transferred to the polymerization reaction vessel before the polymerization reaction is begun or the compound of formula I may be prepared in situ in the polymerization vessel.
• Example 2 The reaction procedure described in Example 2 was repeated over a range of temperatures using a reaction mixture of water (5 410 ml), 1% w/w solution of partially hydrolysed poly(vinyl acetate) (173 ml), di-(tert-butyl) diperoxyoxalate (2.5 g) and vinyl chloride monomer (1 kg). Details of the reaction temperature, reaction time, polymer yield and polymer properties are recorded in Table 1 below.
• a mixture of tert-butyl hydroperoxide (70 mmole), pyridine (70 mmole) and anhydrous hexane (100 ml) was placed inside a dry 7.5 1 stainless steel, jacketed autoclave fitted with a stirring means. The autoclave was sealed and cold water was circulated through the autoclave jacket in order to maintain the autoclave temperature at about 10°C.
• a solution of oxalyl chloride (70 mmole) in anhydrous hexane (60 ml) was injected into the autoclave and after a period of 10 minutes the autoclave was evacuated and vinyl chloride monomer (2.5 kg) was added.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymerization Catalysts (AREA)
• Polymerisation Methods In General (AREA)

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Cited By (4)

• 1980
  • 1980-10-13 AU AU75579/81A patent/AU7557981A/en not_active Abandoned
• 1981
  • 1981-09-25 EP EP81304438A patent/EP0049966A1/en not_active Withdrawn
  • 1981-10-09 ES ES506156A patent/ES8206559A1/es not_active Expired
  • 1981-10-13 JP JP56163360A patent/JPS5794010A/ja active Pending

Non-Patent Citations (3)

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